Evaluation the patient satisfaction and dimensional stability of upper removable partial denture constructed from two different flexible thermoplastic materials.(BRE-FLEX and PEEK).

The assessor is responsible for all clinical procedure that will be conducted in this study during all the visits:

Panoramic radiograph and periapical radiographs will be made on the prospected abutment teeth to evaluate the crown-root ratio, the apical condition of the abutment and their alveolar bone support.

The preliminary impression will be performed with irreversible hydro-colloid impression material (alginate), The impressions will be poured with type IV dental stone to obtain diagnostic casts. Maxillary Face-bow will be recorded. The diagnostic casts will be mounted on semi adjustable articulator in centric occluding relation to evaluate the interarch distance and occlusal plane.

Special trays will be constructed and Mouth preparation will be performed by preparing guiding planes and rests seats will be prepared opposing to the edentulous area. Final impression will be taken by elastomeric impression material. The impression will be poured into type IV dental stone in order to obtain master cast. The master cast will be surveyed. The proposed design will be as follows: metal framework base saddle for edentulous areas on both sides connected with palatal strap. Aker's clasp on all abutments with buccal retention. The denture base will be tried in with acrylic teeth in patient's mouth. After that, the denture base of the partial denture will be processed incorporation with the metal framework into the two different materials to be evaluated. The first group will receive the partial denture in which the metal framework incorporated with the denture base fabricated from PEEK material. The second group will receive the partial denture in which the metal framework incorporated with the denture base material fabricated from BRE-FLEX.

Inclusion Criteria:

• All patients must have Kennedy class III modification I upper partially edentulous ridges.
• The remaining teeth have good periodontal condition, with no signs of attrition or gingival recession.
• Male or female patient with age range (45-55) and in good medical condition
• All patients have skeletal Angle's class I maxillo-mandibular relationship and have sufficient interarch distance.
• Free from any systemic or neuromuscular disorder that might affect chewing efficiency of masticatory muscles.
• Free from any tempro-mandibular joint disorder.
• The patients have good oral hygiene and low caries index.

Exclusion Criteria:

• Patients having abnormal habits as bruxism or clenching
• Patients having hormonal disorders as diabetes, thyroid or parathyroid hormonal diseases were not included.
• Teeth with compromised bone support.
• Patient with xerostomia or excessive salivation.
• Patient with abnormal tongue behavior and/or size.